Description of route dependencies for computer-based railway signalling systems

Efficient and safe movement of trains on railway lines is assured by railway signalling systems. These systems assure safety of railway transport by preservation of dependencies. A significant fraction of dependencies is related to route setting, i.e., preparation of train travel through the specified running paths. The use of computer technology in modern systems allows for greater functionality and smaller physical devices dimension than older types of systems. This results in increased complexity of track layout and increased area of a single interlocking. Systems with considerable number of routes, over a thousand are becoming increasingly common. The research is concerned with the problem of describing route dependencies in computer-based interlocking configuration. During the research existing solutions have been analyzed and a method of describing route dependencies based on requirements of PKP PLK has been proposed. The proposed solution has been verified by functional testing of prototype interlocking. During the research, a formalism for describing the route has been devised, which allows for dependency realization by track layout independent computer program. In addition, during research algorithms for automatic verification of conflicting route exclusion correctness have been designed, which allows for reduction of effort required for verification of conflicting route exclusion function. The proposed method of describing route dependencies allows for simplification of interlocking design and for automation of application data preparation. The method of implementing dependencies also allows for automation of conflicting route exclusion function verification, which decreased the effort required for verification activities while maintaining the high-quality standards.